Method of placing concrete with a predetermined selected placement of aggregate



June 6, 1967 J, M s Ls o 3,324,207

METHOD OF PLACING CONCRETE WITH A PREDETERMINED SELECTED PLACEMENT 0FAGGREGATE Original Filed July 12, 1963 2 Sheets-Sheet 1 /3 r o l 5] w /661 .I O I.

z/ames M S/w/szane INVENTOR.

BY I 7W E W June 6, 1967 J. M. SHILSTONE METHOD OF PLACING CONCRETE WITHA PREDETERMINED SELECTED PLACEMENT OF AGGREGATE Original Filed July 12,1963 2 Sheets-Sheet 2 INVENTOR.

A 770 IPA/[76' United States Patent 3,324,207 METHOD OF PLACING CONCRETEWITH A PREDETERMINED SELECTED PLACEMENT 0F AGGREGATE James M. Shilstone,R0. Box 13163, Houston, Tex. 77019 Continuation of application Ser. No.294,600, July 12, 1963. This application June 16, 1965, Ser. No. 471,4948 Claims. (Cl. 264-35) This application is a continuation of copendingapplication for United States Letters Patent, Ser. No. 294,- 600, filedJuly 12, 1963.

This invention relates to an improved method of placing concrete andrefers more particularly to a method of placing concrete in whichdifferent aggregates which are selected for their known properties areplaced in predetermined positions in the cast structure.

By way of illustration, but not by way of limitation, the invention willbe primarily described in connection with its use in casting concretestructures having an external face or faces formed of exposed aggregateas a means of beautification of the finished product. However, theinvention also has application to the casting of structures whereinaggregates having different strength, structural, or weightcharacteristics are selected and placed in predetermined positions inthe finished product so as to contribute their particularcharacteristics to at least a major extent to the finished product. Forexample, light weight expanded aggregates (considered objectionable bysome structural engineers because of plastic flow that might take placein a structure over a period of years) may be used throughout a majorsection of a concrete product in which a rigid shell is provided by useof rock aggregate to compensate for the objectionable plastic flow.Thus, a considerable saving in weight may be effected over the use ofall rock aggregate.

The use of exposed aggregate as a means of beautifying concretestructures is coming more and more into vogue. However, in placingconcrete in accordance with conventional techniques, it has beenextremely difiicult to obtain uniformity of distribution of theaggregate over the surface to be exposed so as to prevent a mottledeffect. At best the limitation of the amount of coarse aggregate thatmay be used in pouring concrete provides a rather sparse amount ofcoarse aggregate at the exposed surface for architectural finishes.Further, where the entire structure is cast with high cost aggregatehaving a selected special appearance, the cost of the structure isnearly prohibitive. For these reasons, veneers have been resorted towherein precast panels are hung in place on structural members, but thecost is high and no structural support is provided 'by the panels. Also,a checkerboard appearance is inevitable due to the seams which appearbetween adjacent panels. Some effort has been made to glue aggregateselected for its appearance to a form prior to the casting of concretestructures; but this has not been entirely satisfactory because of highcost of gluing the aggregate in place, the likelihood of aggregate beingdislodge-d during the pouring operation, the difficulty of obtaininguniformity in such a pattern and the special techniques required.

It is an object of this invention to provide a method of castingconcrete structures in which a section or layer of predeterminedthickness and shape may be provided within the form, filled with anaggregate selected for its known characteristics and retained in placeby a perforate barrier while the form is filled with a concrete mixcontaining a different aggregate and sufiicient mortar to flow throughthe barrier and into the spaces between the individual particles of theplaced aggregate. Once the cast structure has sufficiently cured, theform may be 3,3242%? Patented June 6, 1967 ice removed; and if exposedaggregate is desired, the surface motar may be removed by suitableprocedures such as washing, bush hammering, or sand blasting, accordingto known practices.

Another object is to provide a method of casting ex- 'posed aggregateconcrete structures in which the amount of expensive aggregate with goodappearance may be minimized and readily available and relativelyinexpensive aggregate may be used for the remainder of the structure.

Another object is to provide a more economical method of casting exposedaggregate concrete structures which may be readily cast in place usingreadily available equipment.

Another object is to provide a method of casting exposed aggregateconcrete structures in which the aggregate at the exposed face isuniformly distributed.

Another object is to provide a method of casting exposed aggregateconcrete structures in which the exposed faces may be vertical,inclined, or overhead.

Another object is to provide a method of casting exposed aggregateconcrete structures which is adapted to the techniques of use ofchemicals for retarding hardening of the mortar, thereby permittingwashing of mortar from the surface to be exposed.

Another object is to provide a method of casting exposed aggregateconcrete structures which is adapted to the use of techniques involvingthe use of shields to provide designs selectively exposing a portion ofthe aggregate on the removal of mortar to expose the aggregate on thesurface.

Other and further objects will appear from the specification anddescription of preferred embodiments of the invention.

In accordance with this invention, different aggregates are selectedwith known characteristics to perform different functions when locatedin different predetermined sections of the structure to be cast. Atleast one such aggregate is placed in the form and retained therewithout any mortar while a mix of the other aggregate and sufficientmortar to provide the mortar for the placed aggregate is placed into theother section of the form. It is preferred to use vibration whileplacing the concrete mix to force the mortar into the spaces between theplaced aggregate.

In the drawings which form a part of the instant specification and inwhich exemplary methods of this invention are illustrated:

FIG. 1 is a side elevational view illustrating one step in the assemblyof a form in the practice of an embodi ment of this invention;

FIG. 2 is a top plan view illustrating a successive step in the assemblyof the form of FIG. 1;

FIG. 3 is a plan view of the form of FIG. 2 illustrating -a selectedaggregate occupying a predetermined section between the barrier and theform of FIG. 2;

FIG. 4 is a view in vertical section through the ap- Q paratus of FIG. 3after the center core of concrete mix has been placed; and

FIG. 5 is an isometric view illustrating another embodiment of themethod of this invention.

In FIGS. 1 to 4 of the drawings, there is illustrated the stepwisecasting of the vertical column in accordance with the method of thisinvention. FIG. 1 illustrates the mounting of the reinforcement rods 10on the upper end of a lower column or base 11. The reinforcement will beselected and mounted in accordance with usual practices for the servicesin which the structures are to be placed. In the interest of simplicity,cross braces between the reinforcement rods have not been shown as theymay follow any suitable pattern. In most instances, the reinforcementrod may be used to secure the perforate barrier in place in the form soas to divide the interior of the form into sections or compartments. Inthe particular embodiment, the barrier is shown as a hardware cloth 12arranged in overlapping layers. The size of the openings in the barrierwill be determined primarily by the size of the aggregate that isretained in the space or compartment provided by the barrier. Usually,square openings having a dimension from A inch to /2 inch have beenfound to be satisfactory. Briefly, the openings in the barrier should beas large as permissible while still performing the function of retainingthe aggregate in the compartment provided by the barrier. While hardwarecloth has been shown, this is preferred merely because of itsavailability and relatively inexpensiveness. Other materials may beused; and, for example, where the barrier is to terminate at or near anexposed face of the concrete structure, it should be of a material whichwill not corrode or discolor due to weathering. Plastic meshes,fiberglass reinforced plastic, or other suitable materials may be usedunder such circumstances.

In FIG. 1, the barrier is shown as it is being wrapped about thereinforcement rods, and still another section will be wrapped about therods until it terminates adjacent the upper ends of the rods.

After the barrier 12 has been secured in place, the form panels 13 arepositioned as shown in FIG. 2 to complete the assembly and the castingprocedure may be commenced. By reference to FIGS. 2 and 3, it is seenthat the barrier 12 has provided an inner or central section 14 and anouter section 15. It is contemplated that the section 15 may be furtherdivided by the use of vertical :panels or barriers 16 as desired whichmay be either perforate or imperforate. Thus, one aggregate of onecharacteristic size, appearance or color can be placed in chamber 15 onone side of the panel 16 and a different aggregate having a differentcharacteristic size, appearance or color may be placed on the other sideof the panel 16; or the panel 16 may be dispensed with and a singleaggregate used to fill the entire space 15. It is obvious that anyparticular arrangement or placement of panels such as 16 may be used. Inmost instances, where the panels 16 are used, it is preferred to removethem after the aggregate has been placed in the various compartments ofsection 15 divided off by the panels. However, where desired, the panelsmay be left in place during the entire casting process- In the interestof simplicity, the description of the re mainder of the method and ofthe other figures of the drawings will proceed as though the panels 16were not used.

FIG. 3 shows the section 15 filtered or packed with an aggregate 17extending from the bottom of the section 15 to the top. Preferably, theaggregate is usually moistened with water prior to being placed in thesection. In order to obtain a uniform and dense aggregate distributionit is not usually necessary to vibrate either the form or the aggregateitself during the filling of the section 15.

Once section 15 has been completely filled with the aggregate but withno mortar being used, section 14 may then be filled with a concrete mixemploying a different aggregate and sufficient mortar so that the excessmortar will flow through the barrier and infiltrate the spaces betweenthe individual particles of the aggregate 17. As a pour of the concretemix rises in section 14, conventional vibrators are used to force themortar out into the aggregate 17 to fill the spaces or voidstherebetween. The form preferably should be leak tight, i.e.,imperforate. The core mix should utilize materials selected for theirsuitability in meeting the structural requirement of the finishedproduct and according to local availability. The core mix may utilize aslump factor which is consistent wit-h normal practice. It has beenfound, for example, that a core mix having a slump within the range of 3to inches may be employed; and sufiicient workability exists for themortar to flow through the barrier and fill the interstices of theaggregate 17.

Where a tall section 15, for example 10 to 20 feet in height, isinvolved, it may be desirable to fill section 15 in step fashion; thatis, place a part of the aggregate 17 in section 15, and then pour theconcrete mix into secion 14 to just under the height of the aggregate17. This will be repeated until the entire structure been cast.

In FIGS. 3 and 4, the aggregate is illustrated as being being rathersparsely spaced within the concrete mix. This is due to the difficultyof illustration on the part of the draftsman, but is to be noted thataggregate 17 should be tightly packed within chamber 15 in order toobtain uniform results and best appearance when the outer surface mortaris removed to expose the aggregate.

Where the finished product is to have the aggregate exposed on one ormore faces, this may be done in accordance with usual practices. Onemethod for accomplishing this is to utilize a deterrent for hardeningthe cement of the concerte and washing the surface mortar from thestructure after removal of the form. Another method is to sand blast thesurface mortar from the face of the concrete after removal of the form.Also, this is sometimes done by bush hammering the surface mortar fromthe aggregate. In any event, the aggregate having the desired appearancewith uniform distribution will be present and yet the core of thesection will have been formed of a relatively inexpensive, readilyavailable, structurally suitable concrete.

The spacing of the barrier relative to the surface of the form should besuch as to assure a fully packed layer of aggregate but to reduce thelayer to approximately that required, thereby reducing the cost of therelatively expensive aggregate. It is recommended that the spacing ofthe barrier from the form be approximately 1 /2 times the largestaggregate; but where small aggregate size is used, such as A to /2 inch,it is preferred to use a minimum of about one-inch spacing of thebarrier from the form wall. While in the preferred embodiment shown thebarrier is illustrated as mounted directly on the reinforcement, it maybe suspended from the reinforcement or otherwise mounted in the form.However, usually the reinforcement will be located approximately at theproper distance from the form wall for mounting the barrier; and whenthis is true, mounting of the barrier is facilitated.

Destructive tests indicate that any parting line or plane imparted bythe barrier to structures cast by the method of this invention issubstantially negligible from the practical viewpoint. However, ifstructural requirements dictate it, these may be further reduced eitherby using a material with a series of alternate depressions and riseswhether all in one alignment as in corrugated material or at angularalignment such as two directional corrugations for the barrier, orspecial barrier material having barblike extensions extending from oneor either side;

In the embodiment shown in FIGS. 1 to 4, inclusive, the description hasbeen based on the premise that an exposed aggregate was desired.However, it might well be that this would not be the case or that, if itwere the case, still that a desired aggregate having some particularcharacteristic such as for example lightness would be used for castingthe core.

One objection to the use of light weight aggregate such as expandedshales has been that in some uses they have shown a tendency towardplastic flow with time. By the use of stronger non-plastic aggregates inspace 15, such light weight, relatively plastic aggregates can be usedin core 14, there-by greatly reducing the weight factor of the columnand still largely overcoming the deleterious effect of plasticity ofexpanded shales.

Referring to the embodiment of FIG. 5, there is illustrated a method ofcasting a horizontal exposed aggregate structure suitable for casting anoverhead surface or for casting a flat panel which may be used as apre-cast structure. The form panel 18 is supported in a substantiallyhorizontal overhead position. It has a side panel 19 which extendsupwardly approximately to the height of the thickness of the object tobe cast. A selected aggregate 20 is laid on form 19 and barrier 21 issecured over the layer of aggregate 20. The reinforcements 22 are put inplace and barrier 21 is preferably secured to the reinforcements. Thereinforcements extend upwardly at 23 and a portion of barrier 24 alsoextends upwardly to about the top of panel 19 and the reinforcements 23.The aggregate 20 fills the section between panel 19 and barrier 24. Withthis arrangement complete, the core above the reinforcements 22 isfilled with the concrete mix made up of a selected aggregate andsufiicient mortar to flow through the barriers 21 and 24*to fill thespaces between the individual particles of the aggregate 20. The upperlevel of the concrete mix is leveled even with the top edge of panel 19.The structure is permitted to cure at least partially; the form is thenstripped; and the exposed surfaces are treated to remove the exposedmortar either by said blasting, washing or other suitable method.

In the foregoing specification and in the claims, reference is made toselection of different aggregates for their known characteristics. Thisexpression is intended to have a broad meaning and when used encompassesnot only basically different aggregates such as granite chips andgravel, but also the same type of aggregate, such as gravel for example,but sized differently so as to provide an aggregate of restrictivegradation limits for the surface to be exposed so the individualparticles will be more nearly uniform in size. For the non-exposedsection, a broader range of gradation is preferred. However, the termaggregate is used herein to refer to what is sometimes called coarseaggregate, and not to include sand and similar fine material used inmortar and grout, sometimes referred to as fine aggregate.

It will be seen that the ends and objects of this invention have beenaccomplished. There has been provided a method for casting concretebodies in which the bodies may be cast in place in accordance withstandard practices and by use of standard equipment but in whichaggregates may be selected in accordance with known characteristics andplaced in predetermined sections within the cast bodies. By this meanscertain characteristics of aggregates may be imparted to the finishedproduct for one purpose and a different aggregate used either foreconomy or for other desirable characteristics to complete thestructure.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects hereinabove set forth,together with other advantages which are obvious and which are inherentto the process.

It will be understood that certain features and subcom-binations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed 1s:

1. The method of pouring of pouring concrete structures with differentaggregates selected for their known characteristics occupying differentposition in the finished stucture comprising the steps of arranging abarrier and a first aggregate within a removable, imperforate form sothat the first aggregate is retained in and fills a section of the form,and an aggregate-free section is provided in the form with the barrierbetween the sections, the barrier having openings smaller than the sizeof the first aggregate preventing displacement of the first aggregatefrom its section during the step of placing same; and then placing amixture of a second aggregate and mortar into the aggregate-free sectionof the form, the size of the second aggregate being greater than that ofthe barrier openings, the mortar being in sufiicient quantity for a partthereof to flow through the barrier and into the spaces between thefirst coarse aggregate, and vibrating the concrete to cause part of themortar of said mixture to move past the barrier and to the form to fillthe spaces between the pieces of the first coarse aggregate.

2. The method of casting in place a structurally sound concrete columncomprising the steps of securing reinforcement for the column in anupright position; securing a mesh-like barrier to the reinforcement toenclose a space within the barrier; placing a removable, imperforateform about the reinforcement and barrier leaving a space between theinner wall of the form and the barrier of a dimension great enough toreceive a first aggregate therein, said first aggregate being of a sizetoo large to pass through the barrier; packing the space between theform and the barrier with said first aggregate to fill said latterspace; then placing uncured concrete in the section within thereinforcement, said concrete having a mortar component and a componentof a second aggregate, said second aggregate being of a size too largeto pass through the barrier; and vibrating the concrete to cause part ofthe mortar component of the concrete to flow through the barrier and tothe form to fill the voids between the pieces of the first aggregateretained by the barrier.

3. The method of claim 2 wherein said first aggregate next to at leastpart of the form is ornamental in appearance, and the further steps ofat least partially curing the concrete; stripping the form from thestructure and removing at least a part of the surface mortar from theouter portion of the first aggregate to give an exposed aggregateeffect.

4. The method of casting in place a structural-1y sound exposed coarseaggregate horizontal concrete structure comprising the steps ofpositioning a lowermost removable, imperforate form with at least oneside panel rising at least as high as the desired thickness of thefinished horizontal structure; distributing a layer of a first aggregateover the lowermost porton of the form; securing a mesh-like barrier overthe layer of first aggegate in contact therewith, said barrier havingopenings smaller than the size of the first aggregate to retain a fullpack of first aggregate between the lowermost portion of the form andthe barrier, extending the barrier upwardly with the side panel spacedtherefrom a distance to provide a space for receving an additionalquantity of said first aggregate, the barrier extending at least as highas the side panel; filling the space between the barrier and the sidepanel with said additional quantity of said first aggregate; thenplacing uncured concrete in the interior of the barrier, said concretehaving a mortar component and a second aggregate component, said secondaggregate being of a size too large to pass through-the barrieropenings; and vibrating the concrete to cause part of the mortarcomponent of the concrete to flow through the barrier openings and tothe form to fill the voids between the pieces of the first aggregateretained by the barrier; partially curing the concrete; removing theform; and removing at least a portion of the surface mortar from theouter surface of the structure exposed by removal of the form, therebyexposing the surface of part of the first aggregate for aestheticpurposes.

5. The method of casting in place a structurally sound concretestructure utilizing at least first and second aggregates comprising thesteps of assembling a removable,

imperforate form for casting the finished structure, said form beingpartitioned into a plurality of sections by perforate barriers theopenings of which are smaller than the size of the first and secondaggregates but permit the passage of mortar therethrourgh, introducingat least the first aggregate into at least one but not all of thesections to fill the same; then placing uncured concrete in anothersection, said concrete having a mortar component and the secondaggregate as a component, and vibrating the concrete to cause part ofthe mortar component to flow through the barrier and to the form to fillthe voids between the pieces of the aggregate.

6. The method of claim 4 wherein at least some of said first aggregateintroduced into the form prior to the introduction of the concrete hasornamental characteristics and lies adjacent at least one wall of theform, including the further steps of at least partially curing theconcrete; stripping the form from the cast structure, and removing atleast a portion of the mortar from the outer surface of the structureexposed by removal of the form to expose the surface of part of theornamental aggregate.

7. The method of casting in place structurally sound structuresutilizing at least a first and a second aggregates comprising the stepsof arranging a barrier and said first aggregate within a removable,imperforate form with the barrier dividing the form into a plurality ofsections with the first aggregate filling at least one of the sectionsand being retained by the barrier from moving into another one of thesections, said barrier having perforations whereby motar may flowtherethrough but the peforations being too small for the first andsecond aggregates to pass t-herethrough, then placing uncured concretein another section, said concrete having a mortar component and thesecond aggregate as a component, and vibrating the concrete to causepart of the mortar to flow through the barrier and to the form to tillthe voids between the pieces of the first aggregate.

8. The method of casting in place structurally sound concrete structuresutilizing at least first and second aggregates comprising the steps ofarranging reinforcement material with a perforate barrier securedthereto and a removable, imperforate form with the barrier dividing theform into a plurality of separate sections, placing said first aggregateinto all but one of the sections to fill them with the first aggregate,the barrier perforations being smaller than the size of the first andsecond aggregates to prevent passage of said first and second aggregatesthrough the barrier but being pervious to the flow of mortar; thenplacing uncured concrete in said one section, said concrete having amortar component and the second aggregate as a component; and vibratingthe concrete to cause part of the mortar to flow through the barrier andto the form to fill the voids between the pieces of the first aggregate.

References Cited UNITED STATES PATENTS 708,248 9/ 1902 Orlikowski264-112 1,202,341 10/1916 Weisser 264256 XR 1,215,115 2/1917 Connelley264 2,313,110 3/1943 WertZ 25-131 XR FOREIGN PATENTS 561,231 10/ 1944Great Britain. 788,985 1/ 1958 Great Britain.

'ROBERT F. WHITE, Primary Examiner.

R. B. MOFFITT, Assistant Examiner.

1. THE METHOD OF POURING OF POURING CONCRETE STRUCTURES WITH DIFFERENTAGGREGATES SELECTED FOR THEIR KNOWN CHARACTERISTICS OCCUPYING DIFFERENTPOSITIONIN THE FINISHED STRUCTURE COMPRISING THE STEPS OF ARRANGING ABARRIER AND A FIRST AGGREGATE WITHIN A REMOVABLE, IMPERFORATE FORM SOTHAT THE FIRST AGGREGATE IS RETAINED IN AND FILLS A SECTION OF THE FORM,AND AN AGGREGATE-FREE SECTION IS PROVIDED IN THE FORM WITH THE BARRIERBETWEEN THE SECTIONS, THE BARRIER HAVING OPENINGS SMALLER THAN THE SIZEOF THE FIRST AGGREGATE PREVENTING DISPLACEMENT OF THE FIRST AGGREGATEFROM ITS SECTION DURING THE STEP OF PLACING SAME; AND THEN PLACING AMIXTURE OF A SECOND AGGREGATE AND MORTAR INTO THE AGGREGATE-FREE SECTIONOF THE FORM, THE SIZE OF THE SECOND AGGREGATE BEING GREATER THAN THAT OFTHE BARRIER